Uploading files with "german umlaute" in file name > will not display on site

When I upload files via the admin, it changes "umlaute" and remanes the file within the site folder:
Der Datendieb - Hörprobe.mp3 >> Der Datendieb - Hörprobe.mp3

This causes them to not be displayed on the site (FrontEnd). Because there it tries to take the original name.

I also have another strange bug. One file after dragging it in the upload field, it shows the progress then the checkmark, but after hitting save it's not showing up anymore. Anyone any idea?

Hmm, I'm not getting this problem, tried uploading an got Screen Shot 2016-11-17 at 18

Mhm, yes, online that also don't seem to happen anymore. I don't know, maybe is something in my local xampp install or so.